Cytogenetic alterations in eight mammary tumors and tumor-suppressor gene p53 mutation in one mammary tumor from dogs.

OBJECTIVE: To identify mutations in canine mammary tumors. ANIMALS: 10 tumor-bearing dogs. PROCEDURE: Culture of neoplastic cells originating from mammary tumors was performed, and trypsin-G banding was used for cytogenetic investigations. The same tumors were subjected to molecular genetic screening by use of DNA extraction, polymerase chain reaction, DNA elution, and DNA sequencing for ras oncogenes and the p53 tumor suppressor gene.
RESULTS: A broad spectrum of chromosome aberrations was observed, including trisomies, reciprocal translocations, and structural and numerical X-chromosome alterations and deletions. Molecular genetic analysis revealed a tumor suppressor p53 gene mutation in codon 249 of exon 7 in one instance. Interestingly, analyzed mammary tumors were free of mutations in N-ras, K-ras and H-ras, exons 1 and 2.
CONCLUSIONS: Chromosome alterations are wide-spread in canine mammary tumors, but no ras family mutations were detected in tumors from these 10 dogs. CLINICAL RELEVANCE: Knowledge about chromosome, oncogene, and tumor suppressor gene damage could be helpful for diagnosis and prognosis of neoplastic diseases in dogs.